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Desmond C. Ong, Anthony Hayes, David J. Field; Contour change detection in the periphery: threshold as a function of temporal interval. Journal of Vision 2012;12(9):1061. doi: https://doi.org/10.1167/12.9.1061.
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© ARVO (1962-2015); The Authors (2016-present)
We investigate the ability of human observers to detect small rotational changes in elements of a contour as a function of temporal separation and relative position. A contour, made up of seven discrete Gabor elements (SD of 0.16 deg and a centre-to-centre separation of 2 deg visual angle) constructed via co-circular rotation, was presented at different eccentricities in either hemifield (2, 4, and 6 deg). A subsequent stimulus, presented in either hemifield, was either identical to the first, or differed in shape: each element underwent a small rotation, but adhered to the co-circular construction rule. A forced-choice procedure with an adaptive staircase was used to find the minimum rotation threshold for accurate discernment of a change in shape of the contour. We found remarkably consistent performance over a range of inter-stimulus intervals (ISI) from 500 ms to 16 ms (a single frame at 60 Hz). Reduction of the ISI to 0 ms, when presentation of both stimuli was in the same hemifield and eccentricity, resulted in a dramatic drop in threshold, most likely due to the impact of a relative motion cue that is blocked with even a 16 ms ISI. The relative motion cue was also found to be sensitive to small horizontal jitter. We discuss our findings in the context of the change-blindness and contour-integration literatures.
Meeting abstract presented at VSS 2012
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